Maliks Muwatta Book 31, Hadith Number 47.

Section : What is Disapproved in Selling Food with Delayed Payment or Delivery.

Yahya related to me from Malik that Abu’z-Zinad heard Sa’id ibn al-Musayyab and Sulayman ibn Yasar forbid a man to sell wheat for gold on delayed terms and then to buy dried dates with the gold before he had taken delivery of the gold.